1. Field:
This invention relates to catheters or cannulae useful in extracting fluids from the peritoneal cavity.
2. Prior Art:
Catheters and cannulae suitable for removing fluids from the peritoneal cavity are described in U.S. Pat. No. 4,128,173, issued to Lazarus and Nelson.
Another type of peritoneal catheter is described in U.S. Pat. No. 3,459,188 to Roberts.
These prior catheters have sidewall openings which communicate with a central or axial bore to permit fluids external to the catheter, e.g., fluids within the abdominal cavity, to be drawn through the sidewall openings into the central bore and thereafter withdrawn from one end of the catheter which is external to the abdominal cavity. Generally, the sidewall openings of prior catheters are relatively large in relation to the thickness of the catheter, e.g., the Roberts patent at Col. 2, lines 92, et. seq. describes sidewall openings of 0.01 inch to 0.025 inch in diameter.
Previous catheters work well except when tissue clogs the sidewall openings, as may happen when a catheter (or cannula) is inserted through the peritoneum, for example, or when tissue is drawn into the opening. Also, the relatively large openings in the sidewall of a catheter tend to weaken the device. Although catheter breakage has not been a problem, any breakage inside a patient would require surgical removal of the broken part.